Multiplexing on the reverse link feedbacks for multiple forward link frequencies

ABSTRACT

The present patent application comprises a method and apparatus for multiplexing reverse link feedback channels on a single reverse link frequency supporting multiple forward link frequencies for forward link channels, comprising assigning the reverse link frequency to a mobile station, assigning one or more of the forward link frequencies to the reverse link frequency, and code division multiplexing a plurality of the reverse link feedback channels on the reverse link frequency

CLAIM OF PRIORITY UNDER 35 U.S.C. §§119 AND 120

The present Application for patent is a divisional of patent applicationSer. No. 11/297,873, titled “Multiplexing on the Reverse Link Feedbacksfor Multiple Forward Link Frequencies” filed Apr. 3, 2006, pending,which claims priority to Provisional Application No. 60/669,437, titled“Multiplexing on the Reverse Link Feedbacks for Multiple Forward LinkFrequencies” filed Apr. 8, 2005, expired, and assigned to the assigneehereof, and expressly incorporated herein by reference.

FIELD

The present invention pertains generally to communications, and morespecifically to multiplexing feedback information in a multiple carriercommunication system.

BACKGROUND

There is a recent interest in multicarrier transmission systems, whereinmultiple frequencies are used for transmission channels.

SUMMARY OF THE INVENTION

In view of the above, the described features of the present inventiongenerally relate to one or more improved systems, methods and/orapparatuses for communicating speech.

In one embodiment, the present method comprises a method formultiplexing reverse link feedback channels on a single reverse linkfrequency supporting multiple forward link frequencies for forward linkchannels, comprising assigning the reverse link frequency to a mobilestation, assigning one or more of the forward link frequencies to thereverse link frequency, and code division multiplexing a plurality ofthe reverse link feedback channels on the reverse link frequency.

In another embodiment, the present apparatus comprises a communicationapparatus configured to multiplex reverse link feedback channels on asingle reverse link frequency supporting multiple forward linkfrequencies for forward link channels, comprising a transmitter, areceiver operably connected to the transmitter, a processor operablyconnected to the transmitter and the receiver, and memory operablyconnected to the processor, wherein the communication apparatus isadapted to execute instructions stored in the memory comprisingassigning the reverse link frequency to a mobile station, assigning oneor more of the forward link frequencies to the reverse link frequency,and code division multiplexing a plurality of the reverse link feedbackchannels on the reverse link frequency.

Further scope of the applicability of the present method and apparatuswill become apparent from the following detailed description, claims,and drawings. However, it should be understood that the detaileddescription and specific examples, while indicating preferredembodiments of the invention, are given by way of illustration only,since various changes and modifications within the spirit and scope ofthe invention will become apparent to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects, and advantages of the presently disclosed methodand apparatus will become more apparent from the detailed descriptionset forth below when taken in conjunction with the drawings in whichlike reference characters identify correspondingly throughout andwherein:

FIG. 1A is a wireless communication system;

FIG. 1B is a wireless communication system supporting high data ratetransmissions;

FIG. 2 is a block diagram of an Access Network (AN) in a wirelesscommunication system;

FIG. 3 illustrates generation of Feedback Multiplexing Mask according toone embodiment;

FIG. 4 illustrates multiplexing of reverse link frequencies in amulticarrier communication system;

FIG. 5 is a flowchart illustrating the steps executed when multiplexingreverse link frequencies in a multicarrier communication system;

FIGS. 6A and 6B illustrate a traffic channel assignment message;

FIG. 7 is a functional block diagram illustrating an embodiment of anaccess terminal; and

FIG. 8 is a functional block diagram illustrating the multiplexing ofreverse link frequencies in a multicarrier communication system.

DETAILED DESCRIPTION OF THE INVENTION

Communication systems, and wireless systems in particular, are designedwith the objective of efficient allocation of resources among a varietyof users. Wireless systems in particular aim to provide sufficientresources to satisfy the requirements of all subscribers whileminimizing costs. Various scheduling algorithms have been developed,each based on a predetermined system criteria.

In a wireless communication system employing a code division-multipleaccess (CDMA) protocol, one scheduling method assigns each of thesubscriber units all code channels at designated time intervals on atime multiplexed basis. A central communication node, such as a basestation (BS) implements the unique carrier frequency or channel codeassociated with the subscriber to enable exclusive communication withthe subscriber. Time division multiple access (TDMA) protocols may alsobe implemented in landline systems using physical contact relayswitching or packet switching. A CDMA system may be designed to supportone or more standards such as: (1) the “TIA/EIA/IS-95-B MobileStation-Base Station Compatibility Standard for Dual-Mode WidebandSpread Spectrum Cellular System” referred to herein as the IS-95standard; (2) the standard offered by a consortium named “3rd GenerationPartnership Project” referred to herein as 3GPP; and embodied in a setof documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS25.213, and 3G TS 25.214, 3G TS 25.302, referred to herein as the W-CDMAstandard; (3) the standard offered by a consortium named “3rd GenerationPartnership Project 2” referred to herein as 3GPP2, and TR-45.5 referredto herein as the cdma2000 standard, formerly called IS-2000 MC, or (4)some other wireless standard.

The CDMA system allows for voice and data communications between usersover a terrestrial link. In a CDMA system, communications between usersare conducted through one or more base stations. In wirelesscommunication systems, forward link (FL) refers to the channel throughwhich signals travel from a base station to a subscriber station, andreverse link (RL) refers to channel through which signals travel from asubscriber station to a base station. By transmitting data on a reverselink to a base station, a first user on one subscriber stationcommunicates with a second user on a second subscriber station. The basestation receives the data from the first subscriber station and routesthe data to a base station serving the second subscriber station.Depending on the location of the subscriber stations, both may be servedby a single base station or multiple base stations. In any case, thebase station serving the second subscriber station sends the data on theforward link. Instead of communicating with a second subscriber station,a subscriber station may also communicate with a terrestrial Internetthrough a connection with a serving base station. In wirelesscommunications such as those conforming to the IS-95 standard, forwardlink and reverse link signals are transmitted within disjoint frequencybands.

At any given time, each base station may be expected to maintainconcurrent wireless communication links with numerous mobile units. Toreduce interference between the concurrent wireless communication links,the base station and the mobile units in the wireless communicationsystem modulate signals transmitted on the assigned traffic channelsusing a predetermined PN code that uniquely identifies the mobile unit.Thus, the mobile is distinguished from other mobiles by its long PN codewhich may be generated by a long code mask. In IS-95 CDMA, PN code setsare generated using linear feedback shift registers (LFSR).

In a wireless communication system operating according to the CDMA 2000standard, a long code mask may also be used to differentiate reverselink transmissions, i.e. from the mobile unit to the base station, overdifferent traffic channels. The long code mask in CDMA 2000 is a 42-bitnumber that serves as a logical address for Reverse CDMA Channelspreading codes. It is used to select specific bits from the long codelinear feedback shift register to be added, modulo-two, in order toproduce the actual long PN code, at the proper phase. The resultant ofthe sum, that is, the modulo-2 inner product of the generator state withthe mask, is the generator output, or PN code, corresponding to thatmask and is used to identify a particular access terminal or mobilestation. The use of this 42-bit distinct user long code sequence allowsseparation of 2⁴²⁻¹ different user (or mobile) signals at the basestation.

FIG. 1A serves as an example of a communications system 100 thatsupports a number of users and is capable of implementing at least someaspects and embodiments of the invention. The communication system 100comprises a number of communication apparatuses. Any of a variety ofmethods may be used to schedule transmissions in system 100. System 100provides communication for a number of cells 102A through 102G, each ofwhich is serviced by a corresponding base station 820A through 820G,respectively. In the exemplary embodiment, some of base stations 820have multiple receive antennas and others have only one receive antenna.Similarly, some of base stations 820 have multiple transmit antennas,and others have single transmit antennas. There are no restrictions onthe combinations of transmit antennas and receive antennas. Therefore,it is possible for a base station 820 to have multiple transmit antennasand a single receive antenna, or to have multiple receive antennas and asingle transmit antenna, or to have both single or multiple transmit andreceive antennas.

Increasing demand for wireless data transmission and the expansion ofservices available via wireless communication technology have led to thedevelopment of specific data services. One such service is referred toas High Data Rate (HDR). An exemplary HDR service is proposed in“EIA/TIA-IS856 cdma2000 High Rate Packet Data Air InterfaceSpecification” referred to as “the HDR specification.” HDR service isgenerally an overlay to a voice communication system that provides anefficient method of transmitting packets of data in a wirelesscommunication system. As the amount of data transmitted and the numberof transmissions increases, the limited bandwidth available for radiotransmissions becomes a useful resource

FIG. 1B illustrates an architecture reference model for a communicationsystem 100 having an access network 122 communicating with an accessterminal (AT), 106 via an air interface 124. An access network 122 isdefined as network equipment which provides data connectivity between apacket switched data network (typically the Internet) and one or moreaccess terminals 106. An access terminal 106 is equivalent to a mobilestation or a remote station and provides data connectivity to a user. Inone embodiment, the system 120 is a CDMA system having a High Data Rate,HDR, overlay system, such as specified the HDR standard. The AN 122communicates with AT 106, as well as any other ATs 106 within system 120(not shown), by way of the air interface 124. The AN 122 includesmultiple sectors, wherein each sector provides at least one channel. Achannel is defined as the set of communication links for transmissionsbetween the AN 122 and the ATs within a given frequency assignment. Achannel consists of a forward link for transmissions from a base station820 in the AN 122 to AT 106 and a reverse link for transmissions fromthe AT 106 to the BS 820 in the AN 122. The BS 820 is operably connectedto a base station controller (BSC) 810 as illustrated in FIG. 2.

For data transmissions, the AN 122 receives a data request from the AT106. The data request specifies the data rate at which the data is to besent, the length of the data packet transmitted, and the sector fromwhich the data is to be sent. The AT 106 determines the data rate basedon the quality of the channel between AN 122 and AT 106. In oneembodiment the quality of the channel is determined by thecarrier-to-interference ratio (C/I). Alternate embodiments may use othermetrics corresponding to the quality of the channel. The AT 106 providesrequests for data transmissions by sending a data rate control (DRC)message via a specific channel referred to as the DRC channel. The DRCmessage includes a data rate portion and a sector portion. The data rateportion indicates the requested data rate for the AN 122 to send thedata, and the sector indicates the sector from which the AN 122 is tosend the data. Both data rate and sector information are typicallyrequired to process a data transmission. The data rate portion isreferred to as a DRC value, and the sector portion is referred to as aDRC cover. The DRC value is a message sent to the AN 122 via the airinterface 124. In one embodiment, each DRC value corresponds to a datarate in kbits/sec having an associated packet length according to apredetermined DRC value assignment. The assignment includes a DRC valuespecifying a null data rate. In practice, the null data rate indicatesto the AN 122 that the AT 106 is not able to receive data. In onesituation, for example, the quality of the channel is insufficient forthe AT 106 to receive data accurately.

In operation, the AT 106 continuously monitors the quality of thechannel to calculate a data rate at which the AT 106 is able to receivea next data packet transmission. The AT 106 then generates acorresponding DRC value; the DRC value is transmitted to the AN 122 torequest a data transmission. Note that typically data transmissions arepartitioned into packets. The time required to transmit a packet of datais a function of the data rate applied.

This DRC signal also provides the information, which a channel scheduler812 uses to determine the instantaneous rate for consuming information(or receiving transmitted data) for each of the remote stations 106associated with each queue. According to an embodiment, a DRC signaltransmitted from any remote station 106 indicates that the remotestation 106 is capable of receiving data at any one of multipleeffective data rates.

One example of a communication system supporting HDR transmissions andadapted for scheduling transmissions to multiple users is illustrated inFIG. 2. FIG. 2 is detailed hereinbelow, wherein specifically, a basestation 820 and base station controller (BSC) 810 interface with apacket network interface 806. Base station controller 810 includes achannel scheduler 812 for implementing a scheduling algorithm fortransmissions in system 120. The channel scheduler 812 determines thelength of a service interval during which data is to be transmitted toany particular remote station 106 based upon the remote station'sassociated instantaneous rate for receiving data (as indicated in themost recently received DRC signal). The service interval may not becontiguous in time but may occur once every n slots. According to oneembodiment, the first portion of a packet is transmitted during a firstslot at a first time and the second portion is transmitted 4 slots laterat a subsequent time. Also, any subsequent portions of the packet aretransmitted in multiple slots having a similar 4 slots spread, i.e., 4slots apart from each other. According to an embodiment, theinstantaneous rate of receiving data R_(i) determines the serviceinterval length L_(i) associated with a particular data queue.

In addition, the channel scheduler 812 selects the particular data queuefor transmission. The associated quantity of data to be transmitted isthen retrieved from a data queue 830 and provided to the channel element826 for transmission to the remote station 106 associated with the dataqueue 830. As discussed below, the channel scheduler 812 selects thequeue for providing the data, which is transmitted in a followingservice interval using information including the weight associated witheach of the queues. The weight associated with the transmitted queue isthen updated.

Base station controller 810 interfaces with packet network interface806, Public Switched Telephone Network, PSTN, 808, and all base stations820 in the communication system (only one base station 820 is shown inFIG. 2 for simplicity). Base station controller 810 coordinates thecommunication between remote stations in the communication system andother users connected to packet network interface 806 and PSTN 808. PSTN808 interfaces with users through a standard telephone network (notshown in FIG. 2).

Base station controller 810 contains many selector elements 816,although only one is shown in FIG. 2 for simplicity. Each selectorelement 816 is assigned to control communication between one or morebase stations 820 and one remote station 106 (not shown). If selectorelement 816 has not been assigned to a given remote station 106, callcontrol processor 818 is informed of the need to page the remote station106. Call control processor 818 then directs base station 820 to pagethe remote station 106.

Data source 802 contains a quantity of data, which is to be transmittedto a given remote station 106. Data source 802 provides the data topacket network interface 806. Packet network interface 806 receives thedata and routes the data to the selector element 816. Selector element816 then transmits the data to each base station 820 in communicationwith the target remote station 106. In the exemplary embodiment, eachbase station 820 maintains a data queue 830, which stores the data to betransmitted to the remote station 106.

The data is transmitted in data packets from data queue 830 to channelelement 826. In the exemplary embodiment, on the forward link, a “datapacket” refers to a quantity of data which is a maximum of 1024 bits anda quantity of data to be transmitted to a destination remote station 106within a predetermined “time slot” (such as 1.667 msec). For each datapacket, channel element 826 inserts the necessary control fields. In theexemplary embodiment, channel element 826 performs a cyclic redundancycheck, CRC, encoding of the data packet and control fields and inserts aset of code tail bits. The data packet, control fields, CRC parity bits,and code tail bits comprise a formatted packet. In the exemplaryembodiment, channel element 826 then encodes the formatted packet andinterleaves (or reorders) the symbols within the encoded packet. In theexemplary embodiment, the interleaved packet is covered with a Walshcode, and spread with the short PNI and PNQ codes. The spread data isprovided to RF unit 828 which quadrature modulates, filters, andamplifies the signal. The forward link signal is transmitted over theair through an antenna to the forward link.

At the remote station 106, the forward link signal is received by anantenna and routed to a receiver. The receiver filters, amplifies,quadrature demodulates, and quantizes the signal. The digitized signalis provided to a demodulator (DEMOD) where it is despread with the shortPNI and PNQ codes and decovered with the Walsh cover. The demodulateddata is provided to a decoder which performs the inverse of the signalprocessing functions done at base station 820, specifically thede-interleaving, decoding, and CRC check functions. The decoded data isprovided to a data sink.

The hardware, as pointed out above, supports variable rate transmissionsof data, messaging, voice, video, and other communications over theforward link. The rate of data transmitted from the data queue 830varies to accommodate changes in signal strength and the noiseenvironment at the remote station 106. Each of the remote stations 106preferably transmits a data rate control signal to an associated basestation 820 at each time slot. The DRC signal provides information tothe base station 820, which includes the identity of the remote station106 and the rate at which the remote station 106 is to receive data fromits associated data queue. Accordingly, circuitry at the remote station106 measures the signal strength and estimates the noise environment atthe remote station 106 to determine the rate information to betransmitted in the DRC signal.

The DRC signal transmitted by each remote station 106 travels through areverse link channel and is received at base station 820 through areceive antenna coupled to RF unit 828. In the exemplary embodiment, theDRC information is demodulated in channel element 826 and provided to achannel scheduler 812 located in the base station controller 810 or to achannel scheduler 832 located in the base station 820. In a firstexemplary embodiment, the channel scheduler 832 is located in the basestation 820. In an alternate embodiment, the channel scheduler 812 islocated in the base station controller 810, and connects to all selectorelements 816 within the base station controller 810.

For multicarrier transmissions, data is transmitted by dividing the datainto several interleaved bit streams and using these to modulate severalcarriers. Multicarrier transmission is a form of frequency divisionmultiplexing. In a CDMA communication system, multicarrier transmissionis used to suppress multipath fading.

In a communication system employing multicarrier transmissions, it maybe the situation that the number of forward link channels is greaterthan the number of reverse link channels. In this situation, there is aneed to transmit multiple RL channels, corresponding to the multiple FLchannels, on a single RL frequency. The RL channels may be channels usedfor feedback of information. In one example, such a RL channel is theDRC channel as specified in IS-856; in another example, such a RLchannel is an ACKnowledge (ACK) channel used for Automatic RepeatreQuest (ARQ) feedback. According to one embodiment, the RL overheadchannels are multiplexed together on a single RL frequency, wherein along code mask (LCM) is used to code multiplex the overhead channels.Thus, the RL overhead channels used for the ACK channel and the DRCchannel respectively are separated by code division multiplexing usingthe long code mask.

The AN 122 may assign one or more long code masks to the AT 106 for eachof the RL feedback channels on which the access terminal 106 maytransmit. The long code mask for each of the RL feedback channels isidentified by the value of a feedback multiplexing index which isprovided by a route update protocol. A route update protocol providesthe means to maintain the route between the access terminal 106 and theaccess network 122

In one embodiment, the AT 106 may set the long code for each channel onthe RL using the 42-bit mask MI_(RTCMAC) illustrated in FIG. 3.MI_(RTCMAC) is the long code mask for the in-phase reverse trafficchannel (or reverse link). MQ_(RTCMAC) is the long code mask for thequadrature-phase reverse traffic channel (or reverse link), where thereverse traffic channel may consist of a pilot channel, a reverse rateindicator (RRI) channel, a DRC channel, an ACK channel and a datachannel. As illustrated in FIG. 3, the LCM includes four bits, 38, 39,40 and 41, that represent the binary index field labeled IDX. However,the values of the bits in field IDX can vary to produce different longcode masks (LCM).

Also shown in FIG. 3, the long code mask contains a 32-bit ATI number(referred to as the Permuted (ATI) field which is derived from the AT's106 access terminal identifier (ATI) as shown, for example, below inequation 2. An ATI derived number is derived from the identifier of theaccess terminal 106. It is derived from the bits representing theidentifier of the access terminal 106.

According to one embodiment, three additional long code masks arecreated for each RL carrier feedback channel by changing the two mostsignificant bits (MSBs) of the LCM, while keeping the 32-bit PermutedATI field the same. For example, if the two most significant bits of theLCM for one FL ACK channel carried on RL carrier frequency “x” is 00,then three other LCMs may be created to represent three additional FLcarrier frequencies whose DRC or ACK channels are transmitted on RLcarrier frequency x by setting the two most significant bits to 01, 10,and 11. (However, it is noted that the present patent application is notlimited to changing two bits. In other embodiments, three or more bitsmay be changed to create additional LCMs. For example, FIG. 3 shows thefour MSBs 38-41 as having variable values.

Thus, using the LCM of FIG. 3 as an example, bits 40 and 41 would takeon the three values 01, 10 and 11, while the 32 bits in the ATI fieldwould not change their value, to identify three additional LCMs. This isillustrated when the first 4 LCMs represented by feedback multiplexingindexes 0 to 3, have an identical value in their ATI field and differ intheir IDX field by the first two bits, 00, 10, 01, and 11. The LCM withMSBs of 00 could represent the DRC channel of FL frequency “a,” whilethe LCM with MSBs of 01 could represent the DRC channel of FL frequency“b.” Likewise, the LCM with MSBs of 10 could represent the ACK channelof FL frequency “a,” while the LCM with MSBs of 11 could represent theACK channel of FL frequency “b.”

As shown in FIG. 3, part of the long code mask is derived from theaccess terminal's identifier. If more than one identifier is assigned tothe access terminal, additional long code masks can be derived for theterminal For example, additional LCMs may be created by the AN 122reserving the value of ATIs (i.e., not assigning them to other ATs 106)and by the AT 106 using the ATI values to construct the 32 leastsignificant bits (LSBs) of the LCM as described herein. In one example,three additional ATIs would allow for construction of a total of 16 longcode masks.

In a communication system employing multicarrier transmissions, it maybe the situation that the number of forward link channels is equal tothe number of reverse link channels. In this situation it is desirableto allow the mobile 106 to turn off transmission of the pilot and datasignals on certain RL frequencies, i.e., turn off the RL frequency. Thisallows the access terminal 106 to conserve transmission power headroom.Such control of transmission (i.e., turn on/off) may be doneautonomously by the access terminal 106. FIG. 4 illustrates therelationship of multiplexed RL frequencies to the multicarrier FLfrequencies.

In one embodiment shown in the flowchart of FIG. 5, a traffic channelassignment (TCA) message is sent by a base station 820 to assign areverse traffic channel or reverse link to a given mobile station 106,i.e., access terminal (step 100).

The traffic channel assignment message, as illustrated in FIGS. 6A and6B, includes a Frame Offset field, a Pilot Pseudo-random Noise Code(Pilot PN) information field, and a MAC Index field as forward trafficchannel information, and includes a DRC (Data Rate Control) informationLength field, a DRC Channel Gain Base field, an ACK Channel Gain field,a DRC Cover Code field, a Number of Sectors field, and a Number ofReverse Active Sets field. It also contains a Message Id field, aMessage Sequence field, an Assigned Channel Included field, a SchedulerTag Included field, a Feedback Multiplexing Enabled field, a SofterHandoff field, a DSC field, a DSC Channel Gain Base field, a RA ChannelGain field, a Number of Forward Channels This Sub Active Set field, anda Reserved field.

The TCA message also includes an Assigned Channel field, a FeedbackEnabled field, a Feedback Multiplexing Index field, a Feedback ReverseChannel Index field, a Sub Active Set Carrier Control Channel field, aThis Sub Active Set Not Reportable field, a DSC For This Sub Active SetEnabled field, and a Next 3 Fields Same as Before field.

In addition, the TCA message includes a Number Reverse Channels Includedfield, a Number Reverse Channels field, a Reverse Channel Configurationfield, a Reverse Band Class field, a Reverse Channel Number field, aReverse Channel Dropping Rank field, a Pilot This Sector Included field,a Forward Channel Index This Pilot field, a Pilot Group ID field, aNumbers Unique Forward Traffic MAC Indices field, a Scheduler Tag field,an Auxiliary DRC Cover Included field, an Auxiliary DRC Cover field, aForward Traffic MAC Index Per Index Enabled field, an AssignedInterlaces field, a Reverse Link MAC index field, and a RAB MAC Indexfield.

The TCA message represents an improvement over the prior art in that itfurther specifies the relationships detailed in FIG. 4. In oneembodiment, the TCA message conveys the feedback multiplexing index tothe mobile 106. As illustrated in the example of FIG. 4 (and theflowchart of FIG. 5) the mobile station 106 then uses the TCA message toassign multiple carrier FL frequencies “a” through “b” to one RLfrequency “x.” (Step 110) The RL frequency x is then used fortransmission of feedback and/or overhead information corresponding toone or more of the FL frequencies a through b.

Next, the corresponding information, e.g. RL feedback channels DRC andACK, is code division multiplexed on the single RL frequency “x” byusing different long code masks for each. (Step 112) For example, theDRC channel for FL carrier frequency “a” is assigned a long code maskrepresented by feedback multiplexing index 0 on RL carrier “x”, whilethe DRC channel for FL carrier frequency “b” is assigned a long codemask represented by feedback multiplexing index “1” on RL carrier x.Likewise, the ACK channel for FL carrier frequency “a” is assigned along code mask represented by feedback multiplexing index “2” on RLcarrier “x”, while the ACK channel for FL carrier frequency “b” isassigned a long code mask represented by feedback multiplexing index “3”on RL carrier x.

In the example of FIG. 4, the RL frequency “z” used for sending data ortraffic may be autonomously turned off (i.e., no transmissions at thisfrequency) to conserve headroom. Thus, a way to conserve headroom is, asstated above, to allow the mobile 106 to turn off transmission oncertain RL frequencies. Is AT 106 headroom limited? (Step 115) If theanswer to step 115 is yes, then turn off RL frequency “z” used forsending data. (Step 120). In addition, the AT 106 sends a message to theBS 820 telling the BS 820 that it has dropped the RL (Step 122).

Also shown in FIG. 4, the base station 820 may assign only one of themultiple carrier FL frequencies, “c”, to one RL frequency “y.” The RLfeedback channels DRC and ACK for FL frequency “c” may be code divisionmultiplexed on the single RL frequency “y” by using different long codemasks for each. For example, the DRC channel for FL carrier frequency“c” is assigned long code mask 0 on RL carrier “y”, while the DRCchannel for FL carrier frequency “b” is assigned the long code maskrepresented by feedback multiplexing index “1” on RL carrier “y.”

Permuted (ATI) is defined as follows:

ATI=(A₃₁,A₃₀,A₂₉, . . . , A₀)  (1)

Permuted(ATI)=(A₀,A₃₁,A₂₂,A₁₃,A₄,A₂₆,A₁₇,A₈,A₃₀,A₂₁,A₁₂,A₃,A₂₅,A₁₆,A₇,A₂₉,A₂₀,A₁₁,A₂,A₂₄,A₁₅,A₆,A₂₈,A₁₉,A₁₀,A₁,A₂₃,A₁₄,A₅,A₂₇,A₁₈,A₉).  (2)

The 42-bit mask MQ_(RTCMAC) is derived from the mask MI_(RTCMAC) asfollows:

MQ _(RTCMAC) [k]=MI _(RTCMAC) [k−1], for k=1, . . . , 41  (3)

MQ_(RTCMAC)[0]=MI_(RTCMAC)[0]⊕MI_(RTCMAC)[1]⊕MI_(RTCMAC)[2]⊕MI_(RTCMAC)[4]⊕MI_(RTCMAC)[5]⊕MI_(RTCMAC)[6]⊕MI_(RTCMAC)[9]⊕MI_(RTCMAC)[15]⊕MI_(RTCMAC)[16]⊕MI_(RTCMAC)[17]⊕MI_(RTCMAC)[18]⊕MI_(RTCMAC)[20]⊕MI_(RTCMAC)[21]⊕MI_(RTCMAC)[24]⊕MI_(RTCMAC)[25]⊕MI_(RTCMAC)[26]⊕MI_(RTCMAC)[30]⊕MI_(RTCMAC)[32]⊕MI_(RTCMAC)[34]⊕MI_(RTCMAC)[41]  (4)

wherein the operator ⊕ denotes the Exclusive OR operation, andMQ_(RTCMAC)[i] and MI_(RTCMAC)[i] denote the i^(th) least significantbit of MQ_(RTCMAC) and MI_(RTCMAC), respectively.

FIG. 7 is a functional block diagram illustrating an embodiment of an AT106. The AT 106 includes a processor 2602 which controls operation ofthe AT 106. The processor 2602 may also be referred to as a CPU. Memory2605, which may include both read-only memory (ROM) and random accessmemory (RAM), provides instructions and data to the processor 2602. Aportion of the memory 2605 may also include non-volatile random accessmemory (NVRAM). The steps illustrated in FIGS. 4 and 5 and the LCMillustrated in FIG. 3 may be stored as instructions located as softwareor firmware 42 located in memory 2605. These instructions may beexecuted by the processor 2602.

The AT 106, which may be embodied in a wireless communication devicesuch as a cellular telephone, may also include a housing 2607 thatcontains a transmitter 2608 and a receiver 2610 to allow transmissionand reception of data, such as audio communications, between the AT 2606and a remote location, such as an AN 122. The transmitter 2608 andreceiver 2610 may be combined into a transceiver 2612. An antenna 2614is attached to the housing 2607 and electrically coupled to thetransceiver 2612. Additional antennas (not shown) may also be used. Theoperation of the transmitter 2608, receiver 2610 and antenna 2614 iswell known in the art and need not be described herein.

The AT 106 also includes a signal detector 2616 used to detect andquantify the level of signals received by the transceiver 2612. Thesignal detector 2616 detects such signals as total energy, pilot energyper pseudonoise (PN) chips, power spectral density, and other signals,as is known in the art.

A state changer 2626 of the AT 106 controls the state of the wirelesscommunication device based on a current state and additional signalsreceived by the transceiver 2612 and detected by the signal detector2616. The wireless communication device is capable of operating in anyone of a number of states.

The AT 106 also includes a system determinator 2628 used to control thewireless communication device and determine which service providersystem the wireless communication device should transfer to when itdetermines the current service provider system is inadequate.

The various components of the AT 106 are coupled together by a bussystem 2630 which may include a power bus, a control signal bus, and astatus signal bus in addition to a data bus. However, for the sake ofclarity, the various busses are illustrated in FIG. 7 as the bus system2630. The AT 106 may also include a digital signal processor (DSP) 2609for use in processing signals. One skilled in the art will appreciatethat the AT 106 illustrated in FIG. 7 is a functional block diagramrather than a listing of specific components.

The methods and apparatuses of FIG. 5 described above are performed bycorresponding means plus function blocks illustrated in FIG. 8. In otherwords, steps 100, 110, 112, 115, 117, 120 and 122 in FIG. 5 correspondto means plus function blocks 3100, 3110, 3112, 3115, 3120 and 3122 inFIG. 8.

The steps illustrated in FIGS. 4 and 5 and the long code maskillustrated in FIG. 3 may be also be stored as instructions located assoftware or firmware 43 located in memory 45 in the base station 820.These instructions may be executed by a processor or processing meanssuch as control unit 822 as shown in FIG. 2.

Those of skill in the art would understand that the data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description are advantageouslyrepresented by voltages, currents, electromagnetic waves, magneticfields or particles, optical fields or particles, or any combinationthereof. Those of skill would further appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. The various illustrative components, blocks, modules, circuits,and steps have been described generally in terms of their functionality.Whether the functionality is implemented as hardware or software dependsupon the particular application and design constraints imposed on theoverall system. Skilled artisans recognize the interchangeability ofhardware and software under these circumstances, and how best toimplement the described functionality for each particular application.As examples, the various illustrative logical blocks, modules, circuits,and algorithm steps described in connection with the embodimentsdisclosed herein may be implemented or performed with a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components such as,e.g., registers and FIFO, a processor executing a set of firmwareinstructions, any conventional programmable software module and aprocessor, or any combination thereof designed to perform the functionsdescribed herein. The processor may advantageously be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, programmable logic device, array of logicelements, or state machine. The software module could reside in RAMmemory, flash memory, ROM memory, EPROM memory, EEPROM memory,registers, hard disk, a removable disk, a CD-ROM, or any other form ofstorage medium known in the art. An exemplary processor isadvantageously coupled to the storage medium so as to read informationfrom, and write information to, the storage medium. In the alternative,the storage medium may be integral to the processor. The processor andthe storage medium may reside in an ASIC. The ASIC may reside in atelephone or other user terminal. In the alternative, the processor andthe storage medium may reside in a telephone or other user terminal. Theprocessor may be implemented as a combination of a DSP and amicroprocessor, or as two microprocessors in conjunction with a DSPcore, etc.

Preferred embodiments of the present invention have thus been shown anddescribed. It would be apparent to one of ordinary skill in the art,however, that numerous alterations may be made to the embodiments hereindisclosed without departing from the spirit or scope of the invention.Therefore, the present invention is not to be limited except inaccordance with the following claims.

1. A method for multiplexing reverse link feedback channels on one firstreverse link frequency supporting multiple forward link frequencies forforward link channels, comprising: assigning the first reverse linkfrequency to a mobile station; assigning at least one of the forwardlink frequencies to said first reverse link frequency; multiplexing aplurality of the reverse link feedback channels on the first reverselink frequency, wherein said reverse link feedback channels are codedivision multiplexed; and turning off a second reverse link frequencythat can be used by the mobile station for sending data.
 2. The methodaccording to claim 1, wherein said reverse link feedback channelscomprise an acknowledge channel and a data rate control channel.
 3. Themethod according to claim 1, wherein said multiplexing the plurality ofthe reverse link feedback channels on said first reverse link frequencycomprises assigning at least one long code mask to said reverse linkfeedback channels, wherein said reverse link feedback channels are codedivision multiplexed.
 4. The method according to claim 1, whereinassigning the first reverse link frequency to a mobile station comprisessending a traffic channel assignment message to said mobile station. 5.The method according to claim 1, further comprising autonomously turningoff said first reverse link frequency.
 6. The method according to claim3, wherein said long code mask for each of said reverse link feedbackchannels is identified by a feedback multiplexing index.
 7. The methodaccording to claim 4, wherein multiplexing the plurality of the reverselink feedback channels on said first reverse link frequency comprisesassigning one or more long code masks to said reverse link feedbackchannels, wherein said reverse link feedback channels are code divisionmultiplexed.
 8. The method according to claim 7, wherein said long codemask for each of said reverse link feedback channels is identified by afeedback multiplexing index.
 9. The method according to claim 6, whereinsaid long code mask comprises an index field and an access terminalidentifier field.
 10. The method according to claim 8, wherein said longcode mask comprises an index field and an access terminal identifierfield.
 11. The method according to claim 1, wherein the forward linkchannels are equal in number to the reverse link feedback channels. 12.The method according claim 1, wherein turning off said second reverselink frequency comprises turning off pilot and data signals on saidsecond reverse link frequency.
 13. A communication apparatus configuredto multiplex reverse link feedback channels on one first reverse linkfrequency supporting multiple forward link frequencies for forward linkchannels, comprising: a transmitter; a receiver operably connected tosaid transmitter; a processor operably connected to said transmitter andsaid receiver; and memory operably connected to said processor, whereinsaid communication apparatus is adapted to execute instructions storedin said memory comprising: assigning the first reverse link frequency toa mobile station; assigning at least one of the forward link frequenciesto said first reverse link frequency; multiplexing a plurality of thereverse link feedback channels on the first reverse link frequency,wherein said reverse link feedback channels are code divisionmultiplexed; and turning off a second reverse link frequency that can beused by the mobile station for sending data.
 14. The communicationapparatus according to claim 13, wherein said reverse link feedbackchannels comprise an acknowledge channel and a data rate controlchannel.
 15. The communication apparatus according to claim 13, whereinsaid multiplexing the plurality of the reverse link feedback channels onsaid first reverse link frequency comprises assigning at least one longcode mask to said reverse link feedback channels, wherein said reverselink feedback channels are code division multiplexed.
 16. Thecommunication apparatus according to claim 13, wherein assigning thefirst reverse link frequency to a mobile station comprises sending atraffic channel assignment message to said mobile station.
 17. Thecommunication apparatus according to claim 13, further comprisingautonomously turning off said first reverse link frequency.
 18. Thecommunication apparatus according to claim 15, wherein said long codemask for each of said reverse link feedback channels is identified by afeedback multiplexing index.
 19. The communication apparatus accordingto claim 16, wherein multiplexing the plurality of the reverse linkfeedback channels on said first reverse link frequency comprisesassigning one or more long code masks to said reverse link feedbackchannels, wherein said reverse link feedback channels are code divisionmultiplexed.
 20. The communication apparatus according to claim 19,wherein said long code mask for each of said reverse link feedbackchannels is identified by a feedback multiplexing index.
 21. Thecommunication apparatus according to claim 18, wherein said long codemask comprises an index field and an access terminal identifier field.22. The communication apparatus according to claim 20, wherein said longcode mask comprises an index field and an access terminal identifierfield.
 23. The communication apparatus according to claim 13, whereinthe forward link channels are equal in number to the reverse linkfeedback channels.
 24. The communication apparatus according to claim13, wherein turning off said second reverse link frequency comprisesturning off pilot and data signals on said second reverse linkfrequency.
 25. A communication apparatus configured to multiplex reverselink feedback channels on one first reverse link frequency supportingmultiple forward link frequencies for forward link channels, comprising:means for assigning the first reverse link frequency to a mobilestation; means for assigning at least one of the forward linkfrequencies to said first reverse link frequency; means for multiplexinga plurality of the reverse link feedback channels on the first reverselink frequency, wherein said reverse link feedback channels are codedivision multiplexed; and means for turning off a second reverse linkfrequency that can be used by the mobile station for sending data. 26.The communication apparatus according to claim 25, wherein said reverselink feedback channels comprise an acknowledge channel and a data ratecontrol channel.
 27. The communication apparatus according to claim 25,wherein the means for multiplexing the plurality of the reverse linkfeedback channels on said first reverse link frequency comprises meansfor assigning at least one long code mask to said reverse link feedbackchannels, wherein said reverse link feedback channels are code divisionmultiplexed.
 28. The communication apparatus according to claim 25,wherein the means for assigning the first reverse link frequency to amobile station comprises means for sending a traffic channel assignmentmessage to said mobile station.
 29. The communication apparatusaccording to claim 25, further comprising means for autonomously turningoff said first reverse link frequency.
 30. The communication apparatusaccording to claim 27, wherein said long code mask for each of saidreverse link feedback channels is identified by a feedback multiplexingindex.
 31. The communication apparatus according to claim 28, whereinthe means for multiplexing the plurality of the reverse link feedbackchannels on said first reverse link frequency comprises means forassigning one or more long code masks to said reverse link feedbackchannels, wherein said reverse link feedback channels are code divisionmultiplexed.
 32. The communication apparatus according to claim 31,wherein said long code mask for each of said reverse link feedbackchannels is identified by a feedback multiplexing index.
 33. Thecommunication apparatus according to claim 30, wherein said long codemask comprises an index field and an access terminal identifier field.34. The communication apparatus according to claim 32, wherein said longcode mask comprises an index field and an access terminal identifierfield.
 35. The communication apparatus according to claim 35, whereinthe forward link channels are equal in number to the reverse linkfeedback channels.
 36. The communication apparatus according to claim25, wherein turning off said second reverse link frequency comprisesturning off pilot and data signals on said second reverse linkfrequency.
 37. A computer-readable medium embodying a set ofinstructions executable by one or more processors, comprising: code forassigning the first reverse link frequency to a mobile station; code forassigning at least one of the forward link frequencies to said firstreverse link frequency; code for multiplexing a plurality of the reverselink feedback channels on the first reverse link frequency, wherein saidreverse link feedback channels are code division multiplexed; and codefor turning off a second reverse link frequency that can be used by themobile station for sending data.